Housing for optical connector and optical connector

ABSTRACT

An optical connector is provided to reliably hold a ferrule assembly in a housing to enable it stable optical connection. The optical connector is able to accomplish stable connection without any concern of displacement of an optical connecting end portion of the ferrule, even if the optical connector is subjected to repeated connecting and disconnecting operations. In the optical connector, a ferrule assemble having a polygonal prism-shaped flange is accommodated and held so as to elastically reciprocate in a housing of a cavity which has a polygonal engaging portion to receive and engage the flange of the ferrule assemble. A protrusion is formed at an end part of each engaging wall in the direction of inserting the ferrule assemble to rise toward an insertion opening for the ferrule assemble, and each protruding portion of the protrusion is provided to have each different rising height thereof.

TECHNICAL FIELD

The present invention relates to a housing for an optical connectorwhich holds a ferrule assembly to be used for transmitting and receivingoptical signals, and an optical connector for equipping the ferruleassembly to the housing.

BACKGROUND

Conventionally, a ferrule which is used as a connecting end of anoptical fiber for transmitting and receiving optical signals in opticalcommunication is usually obtained by forming ceramics consistingprimarily of zirconia into a predetermined shape by injection molding orthe like, and then baking thereof. The ferrule is provided athrough-hole for inserting an optical fiber and is used as a ferruleassembly to hold and fix the optical fiber in the through-hole. Theferrule assembly is widely used in optical connectors that are used toconnect optical fibers together and to establish a communication path,or in a semiconductor laser module that is constituted by asemiconductor laser, the optical fiber and the like.

The optical connector is widely used to transmit the optical signalsemitted from the semiconductor module or the like to another opticalcomponent through the optical fiber, or used as relay members connectedbetween the optical fibers to transmit the optical signals to theoptical component placed at a far distant location. The opticalconnector in this type is a preferred connection configuration thatopposite ferrule ends each other are accurately and closely contactedtherebetween and axis lines of the ferrules (specifically, axis lines ofcores of the ferrules) are aligned each other to efficiently transmitlight from one optical fiber to the other optical fiber. For the opticalconnectors, stability of assembling thereof at an on-site of connectionand protection of connecting portion are required, and further, in orderto minimize connection loss when the optical connectors are mutuallyconnected, it is desirable to accurately align the cores of the opticalfibers, and manufacturing error is required to be eliminated as much aspossible. It is specified that the axis lines of the fiber cores must bealigned within a range of connection error of μm order when the opticalfibers are connected together, so that not only a high degree ofaccuracy is required for shapes and dimensions of componentsconstituting the optical connector which becomes the connection ends,but also the utmost attention must be paid to assembling the opticalconnector.

A communication path is established by inserting the optical connectordescribed above into an opening of a jack socket disposed on a panelsuch as a wall. When the optical connector is inserted into the openingof the jack socket, a latch formed integrally with a housing of theoptical connector is interlocked in the opening of the jack socket andheld in order not to fall easily. In addition, there are many situationsto be used the optical connectors which are oppositely connected in anadapter housing to extend the optical fiber.

An example of the optical connector having the above-describedconfiguration is disclosed, for example, in the Japanese Patent No.3996335 of Patent Document 1. In a conventional optical connector 50shown in FIGS. 8 and 9, a housing 51 which has a rectangular outer shapeand is cylindrically formed a main body, and a cavity 52 is formed inthe housing. A latch 53 is integrally provided on the housing 51, andthe housing 51 is held by interlocking, engaging the latch in theopening of the jack socket fitted to a panel or the like. A ferruleassembly 54 which has a ferrule 55 to establish a communication path isaccommodated in the cavity 52. A compression coil spring 56 is fittedaround the ferrule assembly 54, and the ferrule assembly is retained inthe cavity so as to be elastically advanced or retracted by an elasticresilient force of the compression coil spring 56, and is resilientlyconnected to another opposite ferrule (not shown), and a communicationpath is established. In the drawings, numeral 61 denotes a dust cap forprotecting the ferrule from dust, dirt, and stains.

As specifically shown in FIG. 9, the ferrule assembly 54 has the ferrule55 and a holder 57 which holds it, and the holder 57 has a guide sleeve57 a to guide the compression coil spring 56, and a flange 57 b formedto a hexagonal column shape to be urged by the compression coil spring56. A truncated cone shaped guide portion 57 c which is continued to theflange 57 b is formed in the front portion where the ferrule is fitted.

And, the ferrule assembly 54 is accommodated in the housing 51 in astate that the guide sleeve 57 a is supported by an insertion 58, and anoptical connection end of the ferrule 55 is projected toward an opening51 b of one end of the housing 51. At this time, the holder 57 of theferrule assembly 54 is fitted into a recess 51 a and a recess 51 d whichhave shapes which have corresponding to the holder 57, and as shown inFIG. 8, an opening 51 c of the other end is closed by a sealing memberso that the projection position of the ferrule 55 is established. By thesealing by the sealing member 60, therefore, a front end of a triggerlever 60 a projected from the sealing member 60 is positioned above thelatch 53 of the housing 51. By pressing the trigger lever 60 a downward,the latch 53 opposite thereto descends resistively against an elasticforce, so that an interlock of the optical connector 50 inserted into anopening of a jack socket or the like is released and is able to bepulled out therefrom.

Patent Document 1: Japanese Patent No. 3996335

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

A ferrule and an optical connector are precisely manufactured to achieveaccurate optical connection. And as shown in FIG. 9, a recess 51 d whichhas a hexagonal shape which is provided so as to correspond to the shapeof the flange 57 b is provided in the cavity 52, and the ferruleassembly 54 is normally urged by the compression coil spring 56 to addan appropriate pressing force to the connection end. Therefore, theflange 57 b is accurately and closely engaged with the recess 51 d bythe pressing force of the compression coil spring 56, and the ferruleassembly 54 is mounted in the cavity 52 of the housing 51, then anappropriate communication path to an end of the other side to beconnected is established to perform high-quality signal transmission.

However, when the ferrule assembly 54 is accommodated in the cavity 52through the manufacturing process to assemble the optical connector,there may be a case that, as shown in FIG. 10, the flange 57 b which hasa hexagonal column shape is not closely engaged with the recess 51 d andthe flange is fixed by the urging force of the compression coil spring56. Also, when the optical connector is repeatedly inserted into andpulled out from a jack socket, or repeatedly connected to and removedfrom an adapter for relay, there may be a case that the ferrule assembly54 is fixed in the incomplete state shown in FIG. 10. When an opticalconnection operation is carried out by using the optical connector inwhich the ferrule assembly 54 is held in such an incomplete state, it isimpossible to carry out accurate transmission of optical signals, andlong working hours may be required to conduct operation without knowingthe cause of the connection failure. Moreover, even though precisionwork is performed on components of the optical connector, actuallysubtle and serious eccentricity may occur in the optical connection.Therefore, after assembling the optical connector, it is adjusted thatthe engagement between the flange 57 b and the recess 51 d is releasedonce, and the ferrule assembly 54 is rotated, then the flange 57 b andthe recess 51 d are engaged with each other again at a position that ancondition of an optimum optical connection is obtained. However, also insuch case, there is a risk that the flange 57 b is incompletely engagedwith the recess 51 d.

In view of the above conventional problems, the present inventionprovides a housing for an optical connector and an optical connectorwhich are possessed a reliability of assemblage thereof, and are easyrepeatedly to attach and remove the optical connector, and have highconnection reliability as the optical connector.

Means for Solving the Problems

The subject matter of the present invention is defined by:

(1) a housing for an optical connector, comprising a cavity toaccommodate and hold a ferrule assembly having a polygonal prism-shapeflange and to hold the ferrule assembly to be capable of elasticallyadvancing and retracting thereof, the housing characterized bycomprising,

a polygonal engaging portion provided in the cavity to insert and engagethe flange of the ferrule assembly, and

a protrusion provided at an end side of each engaging wall which formsthe engaging portion in a direction of inserting the ferrule assemblytherein to rise in a direction of an opening for inserting the ferruleassembly, wherein each protruding portion of the protrusion is providedto have different rising height each other;

(2) the housing for an optical connector according to the above reciteditem (1), wherein the each protruding portion rises in a state of acurved surface;

(3) the housing for an optical connector according to the above reciteditem (1), wherein the each protruding portion rises to form a curvedsurface having the same curvature radius;

(4) the housing for an optical connector according to the above reciteditem (1) or (2), wherein the height of the protruding portion which isadjacent to one another is lowered consecutively; and

(5) an optical connector characterized in that a ferrule assembly isheld in a housing by fitting and engaging a flange of the ferruleassembly with the engaging portion of the housing for the opticalconnector according to any of the above recited items (1) to (4).

Effects of the Invention

According to the optical connector of the present invention, the ferruleassembly is rotatively moved around the axis thereof and the flange isalways reliably and closely engaged with the recess which has a shapecorresponding to the shape of the flange so that the ferrule assembly issmoothly accommodated in the cavity in a manufacturing process forassembling the connector, and further the ferrule assembly is held by astable urging force of the spring, therefore, the reliability isincreased at the time of assembling the connector, and there is no riskof decreasing accuracy of connection even when the connector isrepeatedly fitted and removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an optical connector accordingto the present invention.

FIG. 2 is a vertical cross-sectional view of a housing of the opticalconnector according to the invention.

FIG. 3 is a view of the housing of the optical connector as viewed fromthe direction of arrow A in FIG. 2.

FIG. 4 is a schematic development view schematically showing a shape ofa recess of the housing.

FIG. 5A is a side view of a ferrule assembly.

FIG. 5B is a vertical cross-section of the ferrule assembly.

FIG. 6 is a partial vertical cross-sectional view showing a relationshipbetween the housing and the ferrule assembly.

FIG. 7 is a schematic view of a pressing test apparatus.

FIG. 8 is a plan view of a conventional optical connector.

FIG. 9 is a vertical cross-sectional view showing a good assembly stateof a conventional housing for an optical connector and a ferruleassembly.

FIG. 10 is a vertical cross-sectional view showing a bad assembly stateof the conventional housing and the ferrule assembly.

EXPLANATION OF REFERENCE NUMERALS  1: Optical connector  2: Housing  3:Ferrule assembly  4: Insertion  5: Sealing member  6: Latch  9: Ferrule10: Holder 10a: Flange 12: Compression coil spring 13: Cavity 14: Recess14a: Engaging portion 14b: Fitting portion 14c: Protrusion

DESCRIPTION OF PREFERRED EMBODIMENT

Hereinafter, a preferred embodiment for working the present inventionwill be described with reference to the drawings.

FIG. 1 is an exploded perspective view of an optical connector accordingto the present invention, FIG. 2 is a vertical cross-sectional view of ahousing of the optical connector according to the invention, FIG. 3 is aview as shown from the direction of arrow A in FIG. 2, FIG. 4 is aschematic development view explaining a shape of a recess, by spreadingthereof, of the housing of the invention, FIGS. 5A and 5B arerespectively a side view and a vertical cross-sectional view of aferrule assembly, FIG. 6 is a partial vertical cross-sectional viewshowing a relationship between the housing and the ferrule assembly, andFIG. 7 is a schematic view of a pressing test apparatus.

As shown in FIG. 1, an optical connector 1 of the invention is comprisedof a housing 2 which is a main body of equipment, a ferrule assembly 3accommodated in the housing 2, an insertion 4 that guides the ferruleassembly 3, and a sealing member 5. The housing 2 and the sealing member5 are made of a based material of a polyphenylsulfone (PPSU). A cavity13 is formed inside the housing 2 (FIG. 2). On the housing 2, a latch 6is integrally formed with the housing as cantilevered manner to projectfrom the housing by providing a base anchor at a connection end sidethereof. A dust cap 8 is removably mounted to an opening 7 where anoptical connection end of the ferrule is located.

As shown in FIGS. 5A and 5B, a main body of the ferrule assembly 3 iscomprised of a ferrule 9 and a holder 10 that firmly holds the ferrule9. The ferrule 9 is formed from ceramics or zirconia by a known methodsuch as injection molding. On the other hand, the holder 10 is made ofstainless steel or brass. The ferrule 9 has a through-hole 9 a forinserting an optical fiber in the axis direction thereof and is held tothe holder 10 by means of press fitting or adhesive bonding. In theinvention, the ferrule 9 is available to use any of a single modeferrule and a multi mode ferrule. The ferrule 9 is formed into acylindrical shape, and for example, may have an external diameter D ofφ1.25 mm, a length L of 6.4 mm, and an internal diameter d of φ0.125 mm.

The holder 10 is provided with a guide sleeve 10 c which is integrallyformed on the rear end of a flange 10 a of a hexagonal column shape toguide a compression coil spring, and a guide portion 10 b of a shape ofa frustum of a cone is integrally formed on the front end of the flange10 a. On the flange 10 a of a hexagonal column shape in the holder 10,the distance between wall surfaces facing each other is specified as2.54 mm. A flexible tube 11 is inserted and fitted to the guide sleeve10 c of the holder 10, and a compression coil spring 12 is mounted andfitted around the outer circumference of the tube 11. The ferruleassembly 3 is held in an elastically advanceable and retractable mannerby the compression coil spring 12 in the cavity 13. The cylindricalinsertion 4 is inserted from the rear end of the tube 11 and presses anend of the compression coil spring 12, and the sealing member 5 and thehousing 2 are engaged with each other in the longitudinal direction, sothat the ferrule assembly 3 is accommodated in the cavity 13, the end ofthe insertion 4 is projected from an end of the sealing member 5, andthe optical connector is assembled in the same way as the conventionaloptical connector shown in FIG. 8. By this assembling, the ferruleassembly 3 is elastically accommodated in the cavity as shown in FIG. 6.By the engagement of the housing 2 and the sealing member 5, a front endof a trigger lever 5 a of the sealing member 5 is positioned above thelatch 6 of the housing 2.

The cylindrical cavity 13 is formed in the housing 2, and a recess 14which has a shape corresponding to the shape of the holder 10 is formedbetween the cavity 13 and the opening 7 in which a forward end of theoptically connected ferrule 9 is situated. Specifically, the recess 14is provided with a fitting portion 14 b, a shape of which iscorresponded to the truncated cone shape of guide portion 10 b, and theflange 10 a of the hexagonal shape, and a hexagonal shaped engagingportion 14 a which are adjacent to each other. Protrusion 14 c(comprised of a plurality of protruding portions 14 c 1 to 14 c 6) isformed at each side edge of a plurality of wall portions 14 a 1 to 14 a6 of the engaging portion 14 a in the direction of inserting the ferruleassemble (i.e., from each side part or edge of the of the wall portions14 a 1 to 14 a 6 toward the cavity 13). It is preferred that theplurality of the protruding portions 14 c 1 to 14 c 6 is formed to risein a shape of curved surface. The boundary portions between theprotrusion 14 c and the wall portions of the engaging portion 14 a, aresmoothly connected, therefore, the ferrule assembly 3 can be easily andreliably inserted into and held in the housing 2. It is preferred thatthe shape of the curved surface of the each protruding portions areformed to have the same curvature radius R, and the radius R ispreferred to be about 0.45 mm to 0.85 mm. As shown in FIGS. 3 and 4,each rising height L of the protruding portions 14 c 1 to 14 c 6 ispreferred to be 0.24 mm to 0.51 mm to have the respectively varied anddifferent heights thereof. As schematically shown in FIG. 4, it ispreferred that rising heights L1 to L6 of the adjacent protrudingportions are formed such that the heights are successively lowered. Forexample, a rising height L1 of the protruding portion 14 c 1 is set to0.45 mm, and a rising height L2 of the adjacent protruding portion 14 c2 is set to 0.42 mm, and in the same way, from L3 to L6, the respectiverising height thereof is successively lowered by 0.03 mm by changing aprotruding amount. As a result, since the rising height L1 of thehighest protruding portion 14 c 1 is 0.45 mm and the rising height L6 ofthe lowest protruding portion 14 c 6 is 0.30 mm, and the differencebecomes 0.15 mm. In this way, by successive variation of the risingheights of the protruding portion adjacent to one another, the flange 10a of the ferrule assembly 3 is smoothly guided to the protrusion 14 c,and the ferrule assembly 3 is rotated around the axis thereof and easilyheld in the recess 14.

As shown in FIG. 6, optical connection can be achieved by inserting theholder 10 into the recess 14 so that the flange 10 a of the holder 10 isreliably engaged with the engaging portion 14 a. However, if aninsignificant eccentricity occurs, the engagement of the flange 10 a andthe engaging portion 14 a is released, and the ferrule assembly 3 isrotated, and the flange 10 a and the engaging portion 14 a are engagedtogether again in a position where an optimal optical connection can beachieved.

In the example described above, a case in which the flange 10 a of theholder 10 has a hexagonal column shape is described. However, the shapeof the flange 10 a may be a square prism-shape or other polygonalprism-shapes. It is understood that the shape of the flange is notlimited to the shape described in the embodiment since the shape of theflange may be appropriately determined.

In addition, the curvature radius and the rising height of theprotrusion of the invention can be properly changed in design by thoseskilled in the art, and are not limited to the values described above.Although an example is described in which the rising heights of theprotruding portions adjacent to one another is changed in a stepwisemanner, it is possible to form the protruding portions into acontinuously spiral shape as a whole, in which the height is graduallylowered, by smoothly lowering the rising heights of the protrudingportions.

Example

Three optical connectors (samples 1 to 3) of the present invention whichhave protruding portions formed so that the rising heights are loweredfrom 0.45 mm to 0.30 mm to be respectively and lowered 0.03 mm in order,and three conventional optical connectors (samples 4 to 6) which do nothave protrusion are prepared. Then, the ferrule 9 is repeatedly pressedby a pressing test apparatus shown in FIG. 7, and whether or not theferrule 9 returns to a correct position is tested.

The pressing test apparatus is entirely controlled by a controller (CPU)21, and reciprocative movement is repetitively is given to the ferrule 9by reciprocating a plunger 20 a of a cylinder apparatus 20 beingstraight to the ferrule 9. When the ferrule 9 is pressed by the plunger20 a, the ferrule assembly 3 is evacuated in the opening 7 against theforce of the compression coil spring described above. This evacuationoperation becomes an adjustment operation of the eccentric positiondescribed above. The reciprocal movements of the ferrule 9 are detectedby sensors 26 a and 26 b, and the movements are captured by a videocamera 25 and displayed on a monitor 24. An output signal from thesensor 26 is measured by a counter 23 and the result is stored in amemory 22. In spite of evacuation of the ferule 9 after the projectingmovement of the plunger 20 a, if the ferrule 9 does not project to theoriginal position by the elastic force of the compression coil spring,the sensor counts one error, i.e. 1 of the error.

The reciprocal movement of the plunger is performed 50 times for eachsample by using the above-described measurement apparatus, and thenumber of errors was measured. The result is shown in table 1. As seenfrom the result in table 1, for the conventional optical connectors, theerror occurs 9 times in the sample 4, 5 times in sample 5, and 7 timesin the sample 6. On the other hand, for the optical connectors of thepresent invention, it is demonstrated that the error hardly occurs inany of the samples 1 to 3, and only one time error occurred in thesample 3. A large difference in stability when the ferrule assembly iscontained into the housing is observed between the optical connectorobtained by using the housing of the invention which includes protrusionin the cavity and the optical connector obtained by using a conventionalhousing which does not include protrusion.

TABLE 1 Comparative Example Example (Conventional Article) (PresentInvention) Protrusion: Protrusion: Existence Nonexistence Sample SampleSample Sample Sample Sample 1 2 3 4 5 6 Number of 0 0 1 9 5 7 timesCounted Error: (In 50 Times of Operating Test)

The invention claimed is:
 1. A housing for an optical connector,comprising a cavity formed therein to accommodate and hold a ferruleassembly having a holder in the form of a polygonal prism-shape flangeand for holding the ferrule assembly to be capable of elasticallyadvancing and retracting thereof, the housing comprising: a polygonalengaging portion having a plurality of engaging walls provided in thecavity to receive and engage the flange of the ferrule assembly, and aprotrusion provided at an end side of each of the plurality of engagingwalls of the polygonal engaging portion in a direction of inserting theferrule assembly therein to rise in an opening for inserting the ferruleassembly to guide the flange of the ferrule assembly, wherein theprotrusion is comprised of a plurality of protruding portions havingdifferent rising heights from each other.
 2. The housing for an opticalconnector according to claim 1, wherein each of the plurality ofprotruding portion rises in a state of a curved surface.
 3. The housingfor an optical connector according to claim 1, wherein each of theplurality of protruding portion rises to form a curved surface having asame curvature radius.
 4. The housing for an optical connector accordingto claim 1, wherein the heights of the plurality of protruding portionswhich are adjacent to one another are formed to be loweredconsecutively.
 5. An optical connector characterized in that a ferruleassembly is held in a housing by fitting and engaging the flange of theferrule assembly with the engaging portion of the housing for theoptical connector according to claim
 1. 6. The housing for an opticalconnector according to claim 2, wherein the heights of the plurality ofprotruding portions which are adjacent to one another are formed to belowered consecutively.
 7. The housing for an optical connector accordingto claim 1, wherein the heights of the plurality of protruding portionswhich are adjacent to one another are formed to be gradually varied. 8.The housing for an optical connector according to claim 1, wherein aboundary portion between the protrusion and engaging wall portionprovided with the engaging portion is smoothly connected, and theferrule assembly is easily and reliably inserted into and held in thehousing.
 9. The housing for an optical connector according to claim 1,wherein the heights of the plurality of protruding portions which areadjacent to one another are formed to be gradually varied, and theflange of the holder provided with the ferrule assembly which isinserted from the cavity of the housing is smoothly guided by theprotrusion of the housing, and the ferrule assembly is rotated aroundthe axis, and the flange is reliably engaged and held with the engagingportion provided to the recess.
 10. The housing for an optical connectoraccording to claim 1, where the plurality of protruding portions areformed into a continuously spiral shape as a whole to have therespective rising heights thereof being smoothly lowered.
 11. Theoptical connector according to claim 5, wherein each of the plurality ofprotruding portions rises in a state of a curved surface.
 12. Theoptical connector according to claim 5, wherein each of the plurality ofprotruding portions rises to form a curved surface having the samecurvature radius.
 13. The optical connector according to claim 5,wherein the heights of the plurality of protruding portions which areadjacent to one another are formed to be lowered consecutively.
 14. Theoptical connector according to claim 11, wherein the heights of theplurality of protruding portions which are adjacent to one another areformed to be lowered consecutively.
 15. The optical connector accordingto claim 5, wherein the heights of the plurality of protruding portionswhich are adjacent to one another are formed to be gradually varied. 16.The optical connector according to claim 5, wherein a boundary portionbetween the protrusion and the engaging wall portion provided with theengaging portion is smoothly connected, and the ferrule assembly iseasily and reliably inserted into and held in the housing.
 17. Theoptical connector according to claim 5, wherein the heights of theplurality of protruding portions which are adjacent to one another areformed to be gradually varied, and the flange of the holder providedwith the ferrule assembly which is inserted from the cavity of thehousing is smoothly guided by the protrusion of the housing, and theferrule assembly is rotated around an axis, and the flange is reliablyengaged and held with the engaging portion provided to a recess.
 18. Theoptical connector according to claim 5, where the plurality ofprotruding portions are formed into a continuously spiral shape as awhole to have the respective rising heights thereof being smoothlylowered.